Printers and plotters often use integrated cartridges which contain an ink reservoir, an electrically actuated dispensing mechanism, and an electrical interface between the integrated cartridge and the printer. The electrical interface allows the printer to control the dispensing mechanism.
Advanced integrated cartridges may contain onboard memory which is accessible to the printer via the electrical interface. The onboard memory may contain a variety of information including the type of ink cartridge, the kind of ink contained in the cartridge, an estimate of the amount of ink remaining in the ink reservoir, calibration data, error information, and other data. The memory may also contain other proprietary or personal data. As the amount of information that can be stored on printer cartridges increases, the possibility of third party access to the interface and onboard memory becomes more undesirable.
Securing the cartridge memory and interface can be accomplished using secure memory chips or encryption techniques. However, using secure memory chips or encryption can significantly increase the cost of the printing system. The economics of manufacturing, distributing, and using disposable printer cartridges typically requires that relatively simple components and interfaces are used. These simple components and interfaces can allow a third party to easily observe how the interface works and recover data stored on the cartridge. The unsecured nature of the onboard memory and the printer/cartridge interface could compromise any proprietary or personal data stored in the cartridge memory.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.